DESCRIPTION:(adapted form applicant's abstract) In lobster, two signaling pathways are known to exist downstream of the recognition of odor molecules by the sensory dendrites enclosed in aesthetascs. Specific odorants are able to trigger one or both of these pathways, which are thought to co-exist in many olfactory neurons. This proposal addresses the role of several of the signaling proteins in each pathway and examines the possibility of biochemical interactions between the pathways. The functional properties of each component will be assessed through a combination of recombinant DNA, biochemical and electrophysiological techniques. The ability of G protein subunits to associate with distinct dimers and thereby activate one or other signal pathway will be examined, as will the phosphorylation of key proteins in vitro and in intact sensory hairs following stimulation with odorants. Many of the key components of the two signaling systems were cloned during the previous funding period. The Principal Investigator will transfect mutant forms of these proteins into primary cultured olfactory neurons to assess whether they have predicted effects on olfactory transduction.